A Clockwork Yellow

If you want to make an apple pie from scratch, you must first create the universe.

Carl Sagan

I think clocks did as much to squash our spirits as anything else, but the history of time is fascinating, and surprisingly silent given its effects on our culture.

When the Prague Orloj astronomical clock was built, raw materials needed to be churned into the metal parts used to make the massive machine, some of which still exist today. People go to visit it, to take pictures, to, in a word, worship.

The beauty of the rhythm of the universe marked by the clock has been usurped by the idea of the clock itself. An abstract form that takes the concrete form of the clock has become another idol.

And we love idols.

***

What do we value in science classes? What does a child learn about the universe by Skyping with astronauts, by playing with remote telescopes via the internet, by doing simulations of labs on an iPad?

If a teacher does not have the wherewithal to teach about combustion using nothing more than a candle, a match, and a bell jar, an iPad will not help.

Teaching science simply can be stressful--there is simply no place to hide. I can teach about combustion using a chemical equation, balancing the reactants and products with flair, as though that's the point of chemistry, using animated demos to show various colorful molecules combining and breaking to form various new substances. And I used to do just that.

Now I start with water seemingly cast from a lit propane torch.

Which is the point, really--here is a piece of the universe, child, here's what we see. Let's figure out if we can find a pattern here.

Teaching combustion going to the equations first is like teaching someone how to look at a sunflower by analyzing Fibonacci spirals:

Until a child sees the beauty of the sunflower for itself, its powerful symmetry easily seen but not so easily defined without numbers, no sense pushing golden ratios.

The school awards the children who can manipulate the Fibonacci ratio. It's easily tested, and easily mastered even without seeing the symmetry in a flower head, should a child be so motivated. In school, we idolize the abstract.

A child could know the golden ratio without grasping the beauty seen in nature's symmetry, and do just fine in science class.

And so folks go to gawk at a clock in Europe, designed to reveal patterns discovered by humans hundreds of years ago, taking pictures of a machine with little machines, understanding how neither works, nor caring to. And they will show off their photos as we show off our clever students who spout off ratios, and wonder why we feel an ache in our chest as we drift to sleep, feeling that something is not quite right, that something is missing.

I keep a sundial by my classroom window.

Golden ratio image lifted from Sofluid here.
The sunflower is by lucapost released and borrowed under CC via Flickr.
Prague clock by Hector Zenil, via Wikipedia, used under CC.

Food for thought

If you don't eat enough, you lose weight. Assuming you're hanging around the surface of the Earth, losing weight means you're losing mass.

Where does it go?

Many of my students (and many adults) think that the food (mass) gets converted to energy, and that explains the weight loss. While this does happen--the sun's light comes from fusion--we would not survive long if we were nuclear furnaces.

So where does it go?

***

High school science mostly exists in a Newtonian universe, and that's as it should be. While e = mc² has become a cultural icon, you really don't need to know much about it in biology, except to know that's how the sun has managed to bathe us with the energy needed for life for over 4 billion years.

(There are huge reasons to know the consequences of our knowledge, but the consequences are far more easily grasped than the physics behind it.)

I announce first day of class that in Room B362, we live in a Newtonian universe. The amount of mass, or stuff, in a closed system (nothing gets in, nothing gets out) stays the same. Forever.

This is a big deal, the heart of chemistry--despite all the fizzing and hissing and heat and bubbling and light--when all is said and done, you have exactly the same amount of stuff at the end of a reaction that you started with. The stuff has different qualities--but the total amount of stuff stays the same.

A child may rationally think, Ah, well, it's easy--we poop! Except for a squirt or two of bile, though, what you poop is mostly the stuff you couldn't digest--stuff that never got inside of you beyond traveling through the open tube between your mouth and you anus. A lot of this stuff is digested by bacteria partying in your gut--they grow and reproduce, but the stuff of bacteria ultimately comes from the stuff that never truly enters you.

If you don't eat, and if you carefully weigh your stool each day, the total weight of you and your stool will still go down.

Where did the missing mass go?

***

A gallon of gasoline weighs just over 6 pounds. The carbon dioxide produced from a gallon of gasoline weighs around 3 times as much! How is this possible?

When you burn something, you are adding oxygen to fuel, and rearranging the atoms of both. In a clean burn, you end up with just water and carbon dioxide. Gasoline is made up of multiple compounds, about a fifth of it is octane ("oct-" means 8 carbons, "-ane" means all single bonds):

2C₈H₁₈ + 25O₂ -> 16CO₂ + 18H₂0

Gasoline compounds have no oxygen atoms--they are added during combustion. Every carbon atom ends up combined with oxygen has mass.

The energy released was energy "held" by electron arrangements in the gasoline--the electrons are in different configurations but they are exactly the same otherwise. (A ball on a table is exactly the same as a ball on the floor, but the ball on the table has more potential energy.)

Energy had to be put into the system to get the electrons in their high energy configurations--which is what plants do with sunlight using water and carbon dioxide, essentially the reverse of combustion. When you burn gasoline, you are releasing the energy that was transformed from ancient sunlight.

It seems as though the gasoline has less mass after we burn it, since all we see is a tiny bit of water trickling out the tail pipe. Just about all the exhaust today is invisible water vapor and carbon dioxide. For whatever reason, most of us do not think of invisible gasses as having any mass.

So where does the carbon in gasoline go? Through the exhaust and into the air. It's as real as solid oak, but we do not perceive it as such.

For most of us, the tank was full, we drove around, and now the tank is empty. We infer, incorrectly, that the gasoline "disappeared." It did not--it merely transformed when combined with oxygen.

***

So what about food?

Breathe on your hand, what comes out? CO₂ and water vapor. (OK, mostly nitrogen, then unconsumed oxygen, a smidgeon of argon, and then carbon dioxide, but certainly more carbon dioxide than what you breathed in.)  The same stuff spewed out by your ULEV car engine.

If you are starving, that carbon came from, well, you. You are breathing out particles of yourself, particles released as you combined pieces of yourself with oxygen to allow electrons to settle down into more comfortable positions, releasing energy as they did so,

Yes, I know, your nitrogen gets converted to urea, and urea as well as ketones can be peed out. I'll save that part for AP Biology class.

Elementary science: playing with fire

Fire is obvious, so it seems. Pretty much every child recognizes the flame of butane lighter is the same as the flames on the stove or on a lit candle.

A child sees that a fire makes solids things smaller. The grown-ups tell children that fire consumes, that the logs burned up, that fire reduces things to ash.

And pretty much every adult who believes this still lives in the world of alchemy, hoping to turn lead into gold.

My September sophomores know what fire is, no surprise, since September sophomores know everything there is to know about anything.

Before I ever say the words respiration or calorie, I ask them about fire—a few look confused (a good sign in science class), but most give me a knowing smile—they know what it is, they “just can’t put it into words” and when they do, they describe the properties of fire. Not a bad start.

I ask them what you need for a fire, and they know that—fuel, oxygen, something to light it—somewhere in elementary school they learned about the fire triangle.

I then pretend to take out a box full of pure oxygen, and ask them what would happen if I lit a match in it.

***

Most of my sophomores know the photosynthesis/respiration equation before they get to my class:

C₆H₁₂O₆ + 6O₂ => 6CO₂ + 6H₂O with energy released

Sugar + oxygen combined releases carbon dioxide and water

CO₂ + H₂O => C₆H₁₂O₆ + O₂ with energy captured

The kids love writing down equations, it gets them feeling all sciency, and now the stupid teacher isn’t asking stupid questions about stupid fire expecting answers that “can’t be put into words.”

The inevitable “Do we have to know this?” comes from the back corner of the classroom—always the same back corner—but I pretend I don’t hear.

I hold up my propane torch—even the back corner crowd notices now. I promise them I will light it in a minute, but they have to answer a simple couple of questions first. What do I need to make it work. (“Well, duh…”), and what is H2O (“Well, duh…” with an advanced eye roll).

I write the equation for the combustion of propane on the board—it’s similarity to the respiration/photosynthesis equations is glaringly obvious, but not a point I care to make at the moment.

C₃H₈ + 5O₂ => 3CO₂ + 4H₂O

I ask what comes out of the propane torch after the propane as the propane is burned. I consistently get two answers—fire and carbon dioxide. I never get water. I’ve asked hundreds of kids the question, with the equation sitting up on the board, and it’s like H2O is some mysterious stuff stuck to the equation just to make it balanced. The stuff is pretty mysterious when you get down to it.

After our list of stuff that comes out of the torch is made—usually CO2, heat, light, flame, and occasionally propane—I light the torch.


I pass the torch over a cool piece of glass—it could be a large beaker—then pass it over the cool stem of the faucet. The students see the flash of water vapor on the glass. They know it looks like "fog” — but no one wants to say it. It makes no sense. Water from fire? It must be a trick.

To be fair, it pretty much gobsmacks me, too, each time I do this.

And of course, water does not come from fire—it comes from the hydrogen in the propane and the oxygen in the air. Turns out we’re all closet alchemists. We cannot accept the obvious.

***

Chemistry hit puberty  when Antoine LaVoisier realized that fire consumes nothing—it only transforms. If you figure out the amount of stuff with and compare it to the stuff you end up with, it has the same mass.

Exactly the same mass.

All the heat and light and noise that escaped from the dancing flame took nothing away. Energy has no mass, no inertia, no stuff to it. It's not nothing, but it's not mass, either.

So what do we teach a young child about fire? Let them observe a candle, let them see the water rise from the flame, let them cover it with a glass and see the flame die, let them wonder.

Matchstick photo by Sebastian Ritter via Wikipediaa under CC.